Richard Jones, the primary developer behind the Roundup issue tracking system (and also the cool new Python Package Index, described in PEP 301), pointed be towards the Roundup instance being used by the Fresco project. The Fresco instance has some cool custom features which I'm looking at doing on our instance, primarily milestone tracking. Milestone objects in Fresco's tracker are small places to gather tasks and bugs together under a particular release plan. Milestones also have their own workflow, independent of the ones used for bugs/tasks, and other milestone-specific data such as release date.
What I'm wanting to do is to introduce a notion into our Roundup tracker that is similar to Taligent's ideas of Places, or Grooves Spaces (if I understand Groove correctly). A place will most likely be a project, and a project will have its own milestones within it. People hang out in these places, working on issues and other documents of interest. It's what I had envisioned we would do with Plone on our intranet, using CMF Collector as issue manager, but Plone turned out to be too slow, and the way we were using CMF Collector turned out not to scale (when you're building a lot of common-base software and have distinct Collector instances for each project, it's hard to know where to place certain issues. It was also difficult to track personal assignments across many collector instances). What I hope to do with Roundup (and this may or may not happen) is to keep the Place/Project and Milestone objects small and fast, like most Roundup things, so that they exist purely as a way to track project related data in a way that doesn't get in the way of managing the project itself.
I think Taligent was on to something with its People, Places, and Things metaphor (Potel and Cotter 1995), and I think Groove's workspace's offer up something similar - places to set up and tear down during the lifetime of a project that hold everything relevant to a particular project. Roundup's speed and flexibility, along with its email integration, allows for something similar to be made without too much effort (I hope ;).
References
Potel, M., and Cotter, S. Inside Taligent Technology (Addison-Wesley, 1995)